Can You Take Tamiflu Without Confirming You Have The Flu?

In our latest question and answer, the pharmacist discusses whether or not you can take Tamiflu if you don't have a confirmed case of the flu.


My child was prescribed Tamiflu but was not administered any test to confirm she actually has the flu. She did get the flu shot back in October of 2018. I'm concerned about giving her the Tamiflu if there is a chance she doesn't have the flu. I don't know if it can cause harm. Also, since she has had the flu vaccine, what are the chances of the side effects?

Asked by kay On Feb 23, 2019

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Feb 23, 2019


Tamiflu (Oseltamivir) can be taken, even if you haven't had any tests confirming you actually have the flu.

In fact, waiting for a confirmatory laboratory test isn't recommended by the CDC (Centers for Disease Control) since Tamiflu is most effective when given as soon as possible. Per the CDC

"Decisions about starting antiviral treatment should not wait for laboratory confirmation of influenza... Clinical benefit is greatest when antiviral treatment is started as close to illness onset as possible."

Additionally, Tamiflu is approved by the FDA (Food and Drug Administration) not only for the treatment of the flu but also for the prevention of it for those who may have been exposed to the virus.

The dosing regimen for both treatment and prevention is similar, but:

  • When Tamiflu is used to treat the flu (regardless of whether or not it is a confirmed case), it is dosed twice a day for 5 days.
  • When Tamiflu is used for the prevention of the flu, it is dosed once a day for 10 days.

Tamiflu With The Flu Vaccine

There have been no reports of increased side effects in those who have received the flu vaccine and later took Tamiflu. So, the fact that your child had the flu vaccine earlier in the year should have no bearing on whether or not Tamiflu can be used.

The only potential concern between the flu vaccine and Tamiflu is if the live flu vaccine is given too close to when Tamiflu is taken. Administration of both too close together could theoretically decrease the effectiveness of the flu vaccine.

The prescribing information warns to avoid administration of the live flu vaccine from 2 weeks before to 48 hours after taking Tamiflu. From the prescribing information:

"The concurrent use of TAMIFLU with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for TAMIFLU to inhibit replication of live vaccine virus and possibly reduce the efficacy of LAIV, avoid administration of LAIV within 2 weeks before or 48 hours after TAMIFLU administration, unless medically indicated."

The recommendation to separate administration of the live flu vaccine and Tamiflu does not apply to the inactivated flu vaccine (which is more common). That vaccine and Tamiflu can be administered concurrently.

Answer Summary

The Centers for Disease Control (CDC) recommends to start Tamiflu therapy as soon as possible for a suspected case of the flu (influenza). You do not need to have a laboratory confirmed test. Additionally, Tamiflu is used not just for the treatment of flu, but also the prevention of it in those exposed to the virus.

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Office: 716-389-3076

Recent Questions